The present invention refers in general to a process and a system for working a workpiece through numerically controlled machine tools, and in particular to a process and a system for working a workpiece through computer-aided copying techniques.
So far, when it is necessary to realize a copy of a workpiece through machine tools, three different types of techniques have been known and have been applied in the field, obviously starting from the project design of the piece to be copied, and apart from the common realization of drawings on paper, from which production dies are obtained, etc.
These three techniques are:
a) realizing drawings of the xe2x80x9celectronicxe2x80x9d type, that is through Computer Aided Design (CAD) techniques, these drawings being used for generating, through Computer Aided Manufacturing (CAM) techniques, a number of tool paths that the numeric control of the machine tool executes in a known way;
b) realizing a physical model of the workpiece to be copied, to such model a scanning (xe2x80x9cdigitizingxe2x80x9d) technique being applied, such technique allowing to automatically create paths for the numeric control of the machine tool similarly to the above technique a); and
c) realizing a physical model of the workpiece to be copied, to which model the so-called direct copying technique is applied. Based on this technique, the outline of the xe2x80x9cmodelxe2x80x9d workpiece is followed by a feeler pin, directly connected to the copying machine tools that works on the rough workpiece. The electronic control of the machine copier is such as to have algorithms that keep the feeler pin in contact with the model and make the tool move on the same path realized by the feeler pin.
The above procedures (b) and (c) are complicated and costly, since they provide the presence of a model to be copied and of a machine tool provided with a feeler pin; moreover, they are subjected to inaccuracies, since possible model faults are taken to the final copied workpiece. Procedure (a), instead, is not subjected to faults, but has complicated aspects and high costs that are necessary to apply the CAM techniques.
Object of the present invention is solving the above prior-art problems, by providing a process and a system that allow perfectly reproducing workpieces to be worked in an automated way, instant by instant, and simultaneously provide the workshop operator with the possibility of choosing movement directions of working tools according to the best available alternatives, keeping the perfect correspondence between xe2x80x9cvirtualxe2x80x9d workpiece to be realized and xe2x80x9crealxe2x80x9d finished workpiece. Through the process and system of the present invention, it is possible to do without the presence of a model workpiece and of the feeler pin, and to do without all possible sources of errors and inaccuracies, since the model of the workpiece to be copied is stored in the control memory and is not subjected to variations. Moreover, it is possible in this way to do without any technique of the CAM type, with its related costs, thereby obtaining a result that is at least equivalent, but often also superior, as regards yield and accuracy, with respect to CAM techniques themselves.
The above and other objects and advantages of the invention, as will appear from the following description, are obtained by a process and a system as claimed in claims 1 or 2, and 8 or 9, respectively. Preferred embodiments and non-trivial variations of the present invention are claimed in the dependent claims.